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YARA · Signature Base (Florian Roth / Nextron)

SIGNATURE_BASE_MAL_APT_NK_Andariel_Agni

Detects samples of the Agni malware family

MalwareSignature Base (Florian Roth / Nextron)Detection Rule License 1.1Compiles with YARA-X
Author
CISA.gov
Date
2024-07-25
Modified
2026-01-29
Score / Quality
80 / 85

What this rule detects

Detects samples of the Agni malware family

Targets: Windows PE.

It defines 2 patterns (0 text, 2 hex, 0 regex).

Summary generated from the rule's metadata and condition.

Rule source

Download .yar
mal-apt-nk-andariel-agni.yarDetection Rule License 1.1
rule SIGNATURE_BASE_MAL_APT_NK_Andariel_Agni : FILE
{
	meta:
		description = "Detects samples of the Agni malware family"
		author = "CISA.gov"
		id = "ffe3f427-c10a-5ad4-ab29-c0d9b576c30f"
		date = "2024-07-25"
		modified = "2026-01-29"
		reference = "https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-207a"
		source_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/yara/apt_nk_andariel_jul24.yar#L201-L216"
		license_url = "https://github.com/Neo23x0/signature-base/blob/94a1c48d7ab499879287ff611dfe7f9c56376030/LICENSE"
		logic_hash = "302899b65e5a3a6beabbb46e80e3f0ff246c209206cc3a7f871011d68871d0b9"
		score = 80
		quality = 85
		tags = "FILE"

	strings:
		$xor = { 34 ?? 88 01 48 8D 49 01 0F B6 01 84 C0 75 F1 }
		$stackstrings = { C7 44 24 [5-10] C7 44 24 [5] C7 44 24 [5-10] C7 44 24 [5-10] C7 44 24 }

	condition:
		uint16( 0 ) == 0x5a4d and #xor > 100 and #stackstrings > 5
}

Strings (2 patterns)

IdentifierTypeValueModifiers
$xorhex{ 34 ?? 88 01 48 8D 49 01 0F B6 01 84 C0 75 F1 }
$stackstringshex{ C7 44 24 [5-10] C7 44 24 [5] C7 44 24 [5-10] C7 44 24 [5-10] C7 44 24 }

Condition

uint16( 0 ) == 0x5a4d and #xor > 100 and #stackstrings > 5

In plain words (Heuristic)

  • The file must start with “MZ” — a Windows executable (PE).
  • Pattern $xor must occur > 100 times.
  • Pattern $stackstrings must occur > 5 times.

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References

Licence & attribution

Author: CISA.gov

Source repository: Signature Base (Florian Roth / Nextron) @ 94a1c48d7a

Licence: Detection Rule License 1.1 (repository licence)

Original rule

Mirrored via YARA Forge 20260927, which prefixes rule names with the source and adds normalised meta fields.

Rule id: ffe3f427-c10a-5ad4-ab29-c0d9b576c30f

Tags:FILE

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